The present invention relates to an oscillator with a piezoelectric vibrator, in which it is easy to control the oscillation frequency, and in which the oscillation frequency is kept constant over a wide temperature range.
For example, in a crystal oscillator, a trimmer capacitor is needed to control the oscillation frequency, so its construction becomes complex. And the oscillation frequency drifts according to the temperature, so it can be used only in a narrow temperature range. Even in an oscillator having the lowest frequency drift rate, its oscillation frequency drifts about .+-.2 PPM in the temperature range 5.about.35.degree. C., and at temperatures outside of that temperature range the oscillation frequency drifts extremely.